Method for measuring three-dimensional surface shape of membrane mirror

Abstract

The invention discloses a method for measuring a three-dimensional surface shape of a membrane mirror. A measuring system comprises a liquid crystal display, a standard planar mirror, a charge coupled device (CCD), an image acquisition card, a computer and the like, wherein the liquid crystal display displays orthogonal sine stripes input through the computer; the CCD acquires compound stripes which are reflected by the standard planar mirror and the membrane mirror; and the system extracts phases in two orthogonal directions by using Fourier transformation profilometry, calculates phase changes in the two orthogonal directions caused by the membrane mirror, calculates gradient distribution of the membrane mirror according to a relation between gradient and the phase changes, and reconfigures the surface shape according to the gradient. By adopting an orthogonal sine stripe reflection technology, measurement of the surface shape of the membrane mirror can be realized only by acquiringa frame of bar graph reflected by the standard planar mirror and the membrane mirror respectively. A measuring device is simple, low in cost and high in instantaneity; and the problem that the three-dimensional surface shape of the membrane mirror is difficult to measure can be solved effectively.

Description

technical field [0001] The invention relates to an optical measurement method of a three-dimensional surface shape, in particular to a three-dimensional surface shape measurement method of a film base reflector based on orthogonal fringe reflection. Background technique [0002] With the rapid development of space technology, the space optical telescope system is urgently required to have the characteristics of large aperture, ultra-light, short manufacturing cycle, and relatively low research and development costs. Compared with other traditional mirrors, space film mirrors are based on flexible film materials, which have the characteristics of foldable and unfoldable, light weight and low cost. Incomparable advantages of manufacturing technology. Due to the characteristics of the film-based mirror itself, such as being sensitive to the environment and thin in quality, its surface shape cannot be detected by conventional surface shape detection methods. [0003] At presen...

AI Technical Summary

Problems solved by technology

This method has a good effect on the detection of mirrors with rigid materials as the base. However, since this method uses a four-step phase shift method to calculate the phases in the two orthogonal directions, a total of 16 images need to be collected, and the real-time performance is poor. However, the film itself is thin and easily affected by air disturbances, which determines the limitations of this method for surface shape detection of film-based mirrors.

Images